... including the use of the "Transform PAL decoder" which is documented here (I wonder if someone could use these techniques these days to make a good software-defined comb filter for Laserdisc watching purposes!)

Yes - I added 2D and 3D implementations of the Transform PAL filter to ld-decode's PAL decoder a couple of years ago, having read about the algorithm in the Doctor Who Restoration Team articles originally. Modern CPUs are fast enough to run the filter and decoder in real time, and the Transform algorithm works remarkably well, although it still needs some work to get it up to the standard of the BBC implementation.

It's worth noting that some discs have cross-colour "burned in" as a result of having been decoded to component video and re-encoded during mastering, though. See this screenshot which shows three different releases of Fawlty Towers for an example - the older BBC disc decodes cleanly with Transform PAL but the EE disc doesn't (we think it's had a DVE effect applied to recentre the active picture - it's shifted to the right relative to the older disc).